textproduct: Albany

WHAT HAS CHANGED

The Storm Prediction Center (SPC) has issued an upgrade to an Enhanced Risk (level 3 of 5) of severe thunderstorms for areas mainly west of the Hudson Valley this afternoon into this evening. There remains a Slight Risk (level 2 of 5) from around the Hudson Valley east.

A Slight Risk (level 2 of 4) of excessive rainfall has been expanded northward to include the eastern Catskills, mid Hudson Valley, Taconics, Berkshires and Litchfield Hills. Multiple round of downpours could result in scattered instances of flash flooding in these areas.

Smoke is expected to return in some capacity today, with poor air quality and haze.

KEY MESSAGES

1) Widespread showers and thunderstorms are expected this afternoon and evening. Some storms will likely be severe with damaging winds, locally heavy rain, and even an isolated tornado.

2) Additional showers and thunderstorms are expected Tuesday into Wednesday. Again, some strong to severe storms and locally heavy rainfall may occur.

DISCUSSION

KEY MESSAGE 1...

Active day shaping up in terms of severe thunderstorm potential and isolated to scattered flash flooding. The overall evolution of the day is coming into better focus. Initial round of showers with perhaps a few embedded non-severe T-storms, looks to move through late morning through early afternoon associated with a warm front passage. Then late afternoon into early evening, strongly forced clusters/lines of showers/T-storms will likely move across the region from NW to SE. This time frame will be when the greatest threats for severe thunderstorms and flash flooding. HREF/REFS continue to show greater instability developing west of the Hudson Valley this afternoon, with around 1000-1500 J/Kg of SBCAPE lowering to < 1000 J/Kg farther east. While the greatest threat of damaging winds will be across western areas (where SPC has upgraded to an Enhanced Risk), the strong synoptic forcing and 35-45 kt 0-6 km layer wind shear should allow for organized cells/lines to progress south/east across much of the area. One potential wildcard is how smoke moving back in will affect destabilization in the warm sector, although due to the strength of the cyclone and wind field, the smoke may not be too much of a factor. Main threat is damaging wind gusts with a fairly rare 45-59% area west of the Hudson Valley. However, a few tornadoes could also occur with any discrete supercells that may develop along with QLCS features due to 0-1 km storm-relative helicity of 150-250 m2/s2 and fairly low LCL heights < 1 km. As a result, SPC has expanded the 5-9% tornado risk to include most of eastern NY. While not a primary threat, isolated large hail could occur within any supercells.

The other threat is potential for isolated to scattered instances of flash flooding with the second round of convection later this afternoon into this evening. In wake of the warm front passage, PWAT anomalies are forecast to surge to +1 to +3 STDEV with the greatest values south of Albany. This is where WPC expanded the Slight Risk (level 2 of 4), with a Marginal Risk (level 1 of 4) from around Albany north. Most susceptible areas will be urban/poor drainage locations that receive multiple rounds of torrential downpours. Mitigating factors are expected fast storm motions and dry antecedent conditions. The threat would be greater if not for these factors.

The threat for severe storms and flash flooding should dissipate by mid to late evening, as the system's cold front pushes through. Low clouds and scattered showers will remain into early Sunday morning.

KEY MESSAGE 2...

Active pattern looks to continue into next week, as a broad upper level trough remains in place across the Great Lakes and Northeast. After a break on Mon, another cyclone and potent upper level short wave approaching from the north/west look to move across the region Tue into Wed. With strong dynamics and kinematics, strong to severe storms will be possible, although there is low confidence in the evolution of this system, with potential for multiple upper level disturbances and also multiple surface waves/front. Areas where sufficient instability develops would have the best chance of severe storms. PWAT anomalies are forecast to increase to +1 to +2 STDEV across the area from the NAEFS. So locally heavy rainfall may occur, although with expected fast storm motions, any flash flood concerns would be for areas that receive multiple rounds of convection.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12z Sunday...VFR conditions will prevail through this morning, with high/mid level clouds increasing. Other than a brief -SHRA at KGFL, it will otherwise remain dry through 16z. Numerous SHRA will then develop by around 16z-17z as a warm front moves through. Conditions likely start to lower to MVFR levels due to the return of smoke/haze along with the showers. There could be a brief break in the showers around mid afternoon, however additional SHRA with embedded strong to severe TSRA will then move in. The TSRA should track from NW to SE between 21z to 02z. There is now high enough confidence to mention TEMPOs at all TAF sites for the TSRA, with strong winds and IFR conditions. Conditions will also lower to MVFR/IFR this evening as a cold front moves across the region, then gradually improve towards 12z Sunday. Winds today will become southerly and increase to 10-15 kt with gusts of 20-30 kt developing.

Outlook...

Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: High Operational Impact. Breezy. Likely SHRA...TSRA. Tuesday Night: High Operational Impact. Definite SHRA...TSRA. Wednesday: High Operational Impact. Likely SHRA...TSRA. Wednesday Night: Low Operational Impact. Slight Chance of SHRA. Thursday: No Operational Impact. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Air Quality Alert until midnight EDT tonight for CTZ001-013. NY...Air Quality Alert until midnight EDT tonight for NYZ032-033- 038>043-047>054-058>061-063>066-082>084. MA...Air Quality Alert until midnight EDT tonight for MAZ001-025. VT...Air Quality Alert until 11 PM EDT this evening for VTZ013>015.